TW201417617A - Heater power control system - Google Patents

Abstract

A method includes delivering current in parallel to a first resistive heating element, a second resistive heating element and a third resistive heating element during a first operating mode of a hot melt dispensing system, and delivering current in parallel to the first resistive heating element, the second resistive heating element and third and fourth resistive heating elements during a second operating mode of a hot melt dispensing system where the third and fourth resistive heating elements are arranged in series.

Description

Heater power control system

The present invention relates generally to systems for dispensing hot melt adhesives. More particularly, the invention relates to controlling the power used to heat a portion of a dispensing system.

Hot melt dispensing systems are commonly used in the manufacture of assembly lines to automatically disperse one of the adhesives used in packaging materials such as cartons, cartons, and the like. The hot melt dispensing system conventionally includes a material tank, a plurality of heating elements, a pump, and a dispenser. The solid polymer pellets are melted into the tank using a heating element prior to being supplied to the dispenser by a pump. Since the molten pellets are allowed to cool to solid form if they are allowed to cool, the molten pellets must be maintained at a certain temperature from the tank to the dispenser. This typically requires placing the heating element in the tank, pump and dispenser and heating any tubing or hose that connects the components. In addition, conventional hot melt dispensing systems typically utilize a can having a large volume such that an extended dispensing cycle can occur after the pellets contained therein are melted. However, large volumes of pellets in the tank require an extra long period of time to completely melt, which increases the startup time of the system. For example, a typical canister includes a plurality of heating elements lined against the walls of a rectangular gravity feed tank such that the molten pellets along the wall impede the heating element from efficiently melting the pellets at the center of the vessel. The prolonged time required to melt the pellets in such tanks increases the likelihood that the adhesive will "carbonize" or darken due to prolonged thermal exposure.

A method comprising: a first mode of operation in a hot melt dispensing system Delivering current in parallel to a first resistive heating element, a second resistive heating element, and a third resistive heating element; and delivering the current in parallel during a second mode of operation of one of the hot melt dispensing systems The first resistive heating element, the second resistive heating element, and the third and fourth resistive heating elements, wherein the third and fourth resistive heating elements are arranged in series.

A hot melt adhesive system comprises: a furnace, a belt heater, a pump, a furnace base and a controller. The furnace includes a first heater crucible. The band heater surrounds at least a portion of the furnace and includes a resistive heating element. The pump includes a second heater 匣. The furnace substrate is located between the furnace and the pump, allowing a molten adhesive to flow from the furnace to the pump and including a third heater crucible. The controller causes current to be delivered to the resistive heating element, the second heater 匣, and the third heater 在一 in a first mode of operation and causing current to be delivered to the resistive heating in a second mode of operation The component, the third heater 匣, and the first heater 匣 are combined in series with one of the second heater 。.

A method for heating a hot melt dispensing system includes: delivering a current to a pump heater and a first furnace heater in parallel with the pump heater during a heating mode; and applying current during an operating mode Delivered to the first furnace heater in parallel with one of the pump heater and a second furnace heater.

1 is a schematic illustration of a system 10 for dispensing a system of a hot melt adhesive. System 10 includes a cold section 12, a hot section 14, and an air source 16. Air control valve 17 and controller 18. In the embodiment shown in FIG. 1, the cold section 12 includes a vessel 20 and a feed assembly 22 including a vacuum assembly 24, a feed hose 26, and an inlet 28. In the embodiment shown in FIG. 1, the hot section 14 includes a melting system 30, a pump 32, and a dispenser 34. The air source 16 is a source of compressed air that is supplied to components of the system 10 in both the cold section 12 and the hot section 14. The air control valve 17 is connected to the air source 16 via an air hose 35A and selectively controls the air from the air source 16 through the air hose 35B to the vacuum assembly 24 and through the air hose 35C to the motor 36 of the pump 32. flow. Air hose 35D connects air source 16 to dispenser 34 to bypass air control valve 17. Controller 18 is coupled to communicate with various components of system 10, such as air control valve 17, melt system 30, pump 32, and/or dispenser 34 for controlling the operation of system 10.

The components of the cold section 12 can be operated at room temperature without heating. The container 20 can be used in a hopper containing one of the solid binder pellets for use by the system 10. Suitable adhesives can include, for example, a thermoplastic polymer glue such as ethylene vinyl acetate (EVA) or a metallocene-based hot melt adhesive. The feed assembly 22 connects the vessel 20 to the hot section 14 for delivering solid adhesive pellets from the vessel 20 to the hot section 14. Feed assembly 22 includes a vacuum assembly 24 and a feed hose 26. The vacuum assembly 24 is positioned in the container 20. Compressed air from air source 16 and air control valve 17 is delivered to vacuum assembly 24 to create a vacuum that induces solid adhesive pellets to flow into inlet 28 of vacuum assembly 24 and then through the feed soft Tube 26 to hot section 14. The feed hose 26 is sized to have a diameter substantially larger than one of the diameters of the solid adhesive pellets to allow the solid adhesive pellets to flow freely Through one of the feed hoses 26 or other passages. Feed hose 26 connects vacuum assembly 24 to hot section 14.

Solid adhesive pellets are delivered from feed hose 26 to melt system 30. The melting system 30 can include a container (shown in Figure 2) and a plurality of resistive heating elements (shown in Figure 2) for melting the solid adhesive pellets to form a hot melt adhesive in liquid form. The melt system 30 can be sized to have a relatively small adhesive volume (for example, about 0.5 liters) and configured to melt the solid adhesive pellets in a relatively short period of time. Pump 32 is driven by motor 36 to pump hot melt adhesive from melt system 30 through supply hose 38 to dispenser 34. Motor 36 can be driven by a pulse of compressed air from air source 16 and air control valve 17 to drive one of the air motors. Pump 32 can be driven by motor 36 as a linear displacement pump. In the illustrated embodiment, the dispenser 34 includes a manifold 40 and a dispensing module 42. The hot melt adhesive from pump 32 is received in manifold 40 and dispensed via module 42. The dispenser 34 selectively discharges the hot melt adhesive thereby ejecting the hot melt adhesive from the outlet 44 of the module 42 to an article (such as a package, a box, or benefiting from the hot melt dispensed by the system 10). Another object of the adhesive). Module 42 can be one of a plurality of modules that are part of dispenser 34. In an alternate embodiment, the dispenser 34 can have a different configuration, such as a hand held gun-type dispenser. Some or all of the components in the thermal section 14 (including the melt system 30, the pump 32, the supply hose 38, and the dispenser 34) may be heated to allow the hot melt adhesive to pass throughout the hot section during the dispensing process 14 remains in a liquid state.

For example, system 10 can be used to package and seal cardboard packaging and/or Part of an industrial program in a box. In an alternative embodiment, system 10 can be modified as needed for a particular industrial program application. For example, in one embodiment (not shown), the pump 32 can be separate from the melt system 30 and instead attached to the dispenser 34. Supply hose 38 can then connect melt system 30 to pump 32.

2 is a perspective view of one of the melting systems 30. As shown in FIG. 2, the melting system 30 includes a pump 32, a motor 36, a furnace 46, a ribbon heater 48, and a furnace base 50. In FIG. 2, one of the covers, typically located on top of the furnace 46, has been removed so that the internal features of the furnace 46 are visible. The furnace 46 is a solid state in which the solid binder pellets are heated to form one of the hot melt adhesives in a liquid form. The solid adhesive pellets enter the furnace 46 from a hopper (not shown) or feed hose 26. Furnace 46 sits on top of furnace base 50 and may include features such as channels, ribs, and fins to increase the contact surface area within furnace 46. Heat is supplied to the furnace 46 by an internal heating element and/or a band heater 48. In the embodiment shown in Figure 2, heater crucible 52 is located within furnace 46 near the center of the molten vessel. The heater crucible 52 can be a tubular Joule heating element. When current is passed through the heater 匣 52, heat is transferred to the furnace 46. Alternatively, other types of heating elements can be located within the furnace 46.

A band heater 48 surrounds at least a portion of the furnace 46. As shown in FIG. 2, the furnace 46 is generally cylindrical and the band heater 48 is wrapped around a cylindrical tubular structure of the furnace 46. The band heater 48 includes a heating element. In the embodiment shown in FIG. 2, the resistive heating element 54 is embedded within a band heater 48 (shown as dashed line 54). When current passes through the resistive heating element 54, heat is transferred through the band heater 48 and the furnace 46. Belt heating The device 48 can extend upwardly from the bottom of the furnace 46 where the furnace 46 meets the furnace base 50 to cover all or a substantial portion of the furnace 46. Alternatively, the band heater 48 can generally surround the furnace 46 only as the solid adhesive pellets enter the furnace 46.

The furnace base 50 is located below the furnace 46 and the band heater 48. The furnace base 50 contains a passage that allows the molten liquid hot melt adhesive to travel from the furnace 46 to the pump 32. Therefore, once the hot melt adhesive has melted into the furnace 46, it is delivered to the pump 32 via the furnace base 50. The pump 32 then delivers the liquid hot melt adhesive to the dispenser 34 as shown in FIG. The furnace base 50 is heated such that the liquid hot melt adhesive present in the furnace base 50 remains in liquid form and can flow to the pump 32. In the embodiment shown in FIG. 2, the furnace base 50 is heated by a heater crucible 56 that is inserted into the furnace base 50. FIG. 2 illustrates the heater crucible 56 within the furnace base 50. The heater 匣 56 can be similar to a tubular Joule heating element of the heater 匣 52.

As noted above, pump 32 pumps liquid hot melt adhesive from melt system 30 to dispenser 34. Pump 32 may include a heating element to supply heat to pump 32 to ensure that any liquid hot melt adhesive present in pump 32 remains in liquid form. In the embodiment shown in FIG. 2, pump 32 is heated by heater 匣 58 inserted into pump 32. FIG. 2 illustrates heater 匣 58 within pump 32. Heater 匣 58 can be similar to one of the heater 匣 52 and 56 tubular shaped Joule heating elements.

The melting system 30 can also include a temperature sensor 60 to determine the temperature of one or more components of the melting system 30. As shown in FIG. 2, temperature sensor 60 is located between band heater 48 and furnace 46. The temperature sensor 60 can also be located in the melting In the other part of the system 30. Temperature sensor 60 communicates the temperature of melting system 30 to controller 18.

The melting system 30 can be heated in different ways in different modes of operation. For example, at the beginning of a conversion prior to the operation of the initial system 10, the melting system 30 is cold (ambient temperature). In this scenario, it is often necessary to "warm" the melt system 30 prior to adding the solid binder pellets to the furnace 46 to promote proper flow of the adhesive through the system 10. In a first mode of operation (heating mode), the melting system 30 is heated such that several components are "hot" prior to operating the pump 32 to dispense the liquid hot melt adhesive. During the first mode of operation, the band heater 48, the furnace base 50, and the pump 32 are heated. Current is delivered to the resistive heating element 54 to heat the ribbon heater 48, to the heater crucible 56 to heat the furnace substrate 50 and to the heater crucible 58 to heat the pump 32. In one embodiment, current is delivered in parallel to the resistive heating element 54, heater 匣 56, and heater 匣 58 in a first mode of operation to warm the melting system 30. Delivering current in this manner allows the components of the melting system 30 to reach an elevated temperature that will allow the liquid hot melt adhesive to flow from the furnace 46 through the melting system 30 to the dispenser 34.

Once the melting system 30 has warmed to a particular temperature, the melting system 30 is heated in a different manner such that the heat delivered to the system is generally concentrated on the solid adhesive pellets that are being melted or will be introduced into the furnace 46. In this second mode of operation ("Operation Mode"), current is delivered to the heating elements in the melting system 30 in a different manner than in the first mode of operation. During the second mode of operation, the band heater 48, the furnace base 50, and the pump 32 are heated. Current is delivered to the resistive heating element 54 to heat the band heater 48 for delivery to the plus The heat exchanger 56 is heated to the furnace substrate 50, delivered to the heater crucible 52 to heat the furnace 46, and delivered to the heater crucible 58 to heat the pump 32. In one embodiment, current is delivered to the resistive heating element 54, the heater 匣 56, and the heater 匣 52 in series with one of the heater 匣 58 in the second mode of operation. According to this embodiment, during the second mode of operation, the melting system 30 is heated to concentrate the energy to melt into the solid binder pellets of the furnace 46.

While the pump 32 can remain heated in the second mode of operation, it requires less heat when the melt system 30 is in operation. The heat added to the belt heater 48 and the furnace 46 causes the solid adhesive pellets to be melted in the furnace 46 into a liquid hot melt adhesive. The liquid adhesive travels from the furnace 46 through the furnace base 50 to the pump 32. The heat added to the adhesive by the furnace 46, the ribbon heater 48 and the furnace base 50 is substantially sufficient to ensure that the adhesive will remain in liquid form until it reaches the dispenser 34. Pump 32 does not require the addition of additional heat to the adhesive. Excessive heat pump 32 can create disadvantages when system 10 is operatively dispensing an adhesive. For example, excessive heating of the adhesive within the pump 32 has the potential to cause discoloration of the adhesive. By arranging the heating elements of pump 32 and furnace 46 in series during the second mode of operation, the electrical resistance of heaters 52 and 58 reduces the amount of power drawn by heater 匣 52 and the heat generated by heater 匣 52. This allows the pump 32 to remain heated at an appropriate level while also reducing the power used to heat the melting system 30 when the system 10 is in operation.

3 is a circuit diagram illustrating the configuration of a heating element in one embodiment of a melting system 30. Figure 3 illustrates a circuit 62 that includes a control relay 64 (which has a relay coil 64R and a switch contact 64C), current Source 66, heater 匣 52, resistive heating element 54, heater 匣 56 and heater 匣 58 and temperature sensor 60. Control relay 64 and current source 66 are controlled by controller 18 based on operator input and sensed temperature feedback from temperature sensor 60. Circuitry 62 operates in a first mode of operation ("boost mode W") and a second mode of operation ("run mode R").

The switch contact 64C is shown in FIG. 3 for a temperature rise mode W in a first position in which the resistive heating element 54, heater 匣 56 and heater 匣 58 are connected in parallel. Thus, the current from current supply 66 is divided based on the relative resistance of elements 54, 匣 56, and 匣 58. The fraction of the total current flowing through one of the shunts of the shunt is equal to the total resistance (R _T ) of the other branch divided by the sum of the resistance of the branch (R _X ) plus the total resistance R _T of the other branches. Therefore, the larger the resistance R _X , the smaller the fraction of the total current flowing through the branch. In the temperature rising mode W, no current is sent to the heater 匣52.

In the operating mode R, the switch contact 64C is connected in series with the heater 匣 58 and the heater 匣 52. Therefore, in the operation mode R, the fraction of the current flowing through the branch is lowered.

The position of the switch contact 64C is determined by the controller 18. In one embodiment, the controller 18 receives information from the temperature sensor 60 and determines if the melting system 30 has warmed up sufficiently and is at a temperature high enough to transition from the first mode of operation to the second mode of operation. The temperature at which circuit 62 transitions from the first operational (warming) mode to the second operational (operating) mode may depend on the selected solid adhesive. In some embodiments, once temperature sensor 60 is labeled between 100 °F (38 °C) and 500 °F (260 °C) (and more preferably between 200 °F (93 °C) and 450 °F (232 °C) Between) a temperature, circuit 62 from the first mode of operation Transition to the second mode of operation.

Due to the series configuration of the pump heating element 58 and the furnace heating element 52, the power drawn during the operating mode R is lower than the power drawn during the heating mode W. In some embodiments, the power drawn during the operating mode R is less than or equal to 70% of the power drawn during the warming mode W. The current delivered to the heating element during the operating mode R is also lower compared to the warming mode W. In some embodiments, the current delivered during the operational mode R is less than or equal to 70% of the current delivered during the warming mode W. Due to the series configuration of the pump heating element and the furnace heating element and the resistance of the heating elements, the power drawn by the combination of the pump heating element and the furnace heating element during the operating mode R is lower than the pump heating element during the heating mode W The power drawn. In some embodiments, the power drawn by the pump heating element 58 and the furnace heating element 52 during the second mode of operation is less than or equal to 25% of the power drawn by the pump heating element during the heating mode W. In addition, the power drawn by the pump heating element (heater 匣 58) in the operating mode R is significantly lower than the power of the heating mode W. In some embodiments, the power drawn by heater 匣 58 during operating mode R is less than or equal to 10% of the power drawn by heater 匣 58 during warming mode W.

Instance

Table 1 and the following illustrations illustrate one possible embodiment of the heating configuration of the melt system 30.

In this example, the basic wattage of the resistive heating element 54 of the band heater 48 is 1250 watts (W), the basic wattage of the heater 匣 56 of the furnace base 50 is 1000 W, and the heater 泵 58 of the pump 32. The basic wattage is 1500 W and the basic wattage of the heater 匣 52 of the furnace 46 is 500 W. In the first operation (heating) mode, the resistive heating element 54, the heater 匣 56, and the heater 匣 58 are arranged in parallel. This configuration in the first mode of operation draws a total power of 3750 W with a current of 16 amps at 240 volts (V). Since each heating element is powered in parallel, the power drawn by each heating element is equal to its basic wattage (resistive heating element 54 is 1250 W, heater 匣 56 is 1000 W and heater 匣 58 is 1500 W).

In the second operation (running) mode, the resistive heating element 54, the heater 匣 56, and the series combination of the heater 匣 58 and the heater 匣 52 are arranged in parallel. Heater 匣 58 has a resistance of 38.4 ohms and heater 匣 52 has a resistance of 115.2 ohms. Due to the series combination of heater 匣 58 and heater 匣 52, the power drawn by each heater element is different from the power of the first mode of operation. Although the resistive heating element 54 still draws 1250 W and the heater 匣 56 still draws 1000 W, but the heater 匣58 now draws 94 W instead of 1500 W. In addition, the heater 匣52 draws 281 W of power. This configuration in the second mode of operation draws an overall power of 2625 W with a current of 11 amps at 240 V.

While the invention has been described in detail with reference to the exemplary embodiments of the present invention, it is understood that various modifications may be made without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the specific embodiments disclosed, but the invention is intended to cover all embodiments within the scope of the appended claims.

10‧‧‧System

12‧‧‧ Cold section

14‧‧‧hot section

16‧‧‧Air source

17‧‧‧Air control valve

18‧‧‧ Controller

20‧‧‧ container

22‧‧‧Feed assembly

24‧‧‧vacuum assembly

26‧‧‧feed hose

28‧‧‧ Entrance

30‧‧‧Melt system

32‧‧‧ pump

34‧‧‧ dispenser

35A‧‧‧Air hose

35B‧‧ Air hose

35C‧‧‧Air hose

35D‧‧‧Air hose

36‧‧‧Motor

38‧‧‧Supply hose

40‧‧‧Management

42‧‧‧Distribution module/module

44‧‧‧Export

46‧‧‧Furn

48‧‧‧Band heater

50‧‧‧furnace base

52‧‧‧heater/furnace heating element

54‧‧‧Resistive heating elements / dashed lines / components

56‧‧‧Hot heater/匣

58‧‧‧Heater heater/匣/pump heating element

60‧‧‧temperature sensor

62‧‧‧ Circuitry

64‧‧‧Control relay

64C‧‧‧Switch contacts

64R‧‧‧Relay coil

66‧‧‧current source/current supply

Figure 1 is a schematic illustration of one of the systems for dispensing a hot melt adhesive.

Figure 2 is a perspective view of one of the melting systems of the system shown in Figure 1.

Figure 3 is a circuit diagram illustrating the configuration of a heating element in the melting system shown in Figure 2.

18‧‧‧ Controller

52‧‧‧heater/furnace heating element

54‧‧‧Resistive heating elements / dashed lines / components

56‧‧‧Hot heater/匣

58‧‧‧Heater heater/匣/pump heating element

60‧‧‧temperature sensor

62‧‧‧ Circuitry

64‧‧‧Control relay

64C‧‧‧Switch contacts

64R‧‧‧Relay coil

66‧‧‧current source/current supply

Claims (19)

A method for operating a hot melt dispensing system, comprising: delivering current in parallel to a first resistive heating element, a second resistive heating element during a first mode of operation of a hot melt dispensing system And a third resistive heating element; and delivering current in parallel to the first resistive heating element, the second resistive heating element, and third and fourth during a second mode of operation of a hot melt dispensing system A resistive heating element, wherein the third and fourth resistive heating elements are arranged in series. The method of claim 1, further comprising: sensing a temperature of the hot melt dispensing system, wherein once the hot melt dispensing system is at a temperature between 100 °F (38 °C) and 500 °F (260 °C) The current is delivered according to the second mode of operation. The method of claim 1, wherein the power drawn during the second mode of operation is less than or equal to about 70% of the power drawn during the first mode of operation. The method of claim 1, wherein the current delivered during the second mode of operation is less than or equal to about 70% of the current delivered during the first mode of operation. The method of claim 1, wherein the hot melt dispensing system comprises: a furnace heated by the fourth resistive heating element; a belt heater surrounding at least a portion of the furnace, wherein the belt heating The device is heated by the first resistive heating element; a pump is heated by the third resistive heating element; A furnace substrate is located between the furnace and the pump, the furnace substrate allowing molten adhesive to flow from the furnace to the pump, wherein the furnace substrate is heated by the second resistive heating element. The method of claim 5, wherein during the second mode of operation, the third resistive heating element draws less than or equal to about 10% of the power drawn by the third resistive heating element during the first mode of operation Power. The method of claim 5, wherein the power drawn by the third resistive heating element in the first mode of operation is greater than the sum of the third and fourth resistive heating elements in the second mode of operation Power. The method of claim 5, wherein the power drawn by the third and fourth resistive heating elements in the second mode of operation is less than or equal to the third resistive heating element during the first mode of operation Take about 25% of this power. A hot melt adhesive system comprising: a furnace comprising a first heater cartridge; a belt heater surrounding at least a portion of the furnace, the ribbon heater comprising a resistive heating element; a pump, The utility model comprises a second heater crucible; a furnace base located between the furnace and the pump, the furnace substrate allowing a molten adhesive to flow from the furnace to the pump, the furnace base comprising a third heater crucible; And a controller that causes current to be delivered to the resistive heating element, the second heater 匣, and the third heater in a first mode of operation In a second mode of operation, current is caused to be delivered to the resistive heating element, the third heater, and the first heater and one of the second heaters are combined in series. The system of claim 9, further comprising: a control switch that electrically connects the first heater 匣 and the second heater 串联 in series in the second mode of operation. The system of claim 9, further comprising: a temperature sensor for sensing a temperature of the furnace to determine whether current can be delivered in accordance with the second mode of operation. A method for heating a hot melt dispensing system, the method comprising: delivering a current to a pump heater and a first furnace heater in parallel with the pump heater during a heating mode; and in an operating mode During this time, current is delivered to the first furnace heater in parallel with one of the pump heater and one of the second furnace heaters. The method of claim 12, wherein the first furnace heater is positioned generally circumferentially about the furnace, and wherein the second furnace heater is positioned substantially centrally within the furnace. The method of claim 12, further comprising: sensing a temperature of the hot melt dispensing system, wherein once the hot melt dispensing system is at a temperature between 100 °F (38 °C) and 500 °F (260 °C) The current is delivered according to the mode of operation. The method of claim 12, wherein the power drawn during the operational mode is less than or equal to about 70% of the power drawn during the warming mode. The method of claim 12, wherein the current delivered during the operational mode is less than or equal to about 70% of the current delivered during the warming mode. The method of claim 12, wherein during the operating mode, the pump heater draws less than or equal to about 10% of the power drawn by the pump heater during the warming mode. The method of claim 12, wherein the power drawn by the pump heater in the warming mode is greater than the power drawn by both the pump heater and the second furnace heater in the operating mode. The method of claim 12, wherein the power drawn by the pump heater and the second furnace heater in the operating mode is less than or equal to about 25 of the power drawn by the pump heater during the warming mode %.